Method of widening crotch angles of fruit trees



States Patent 3,323,894 METHOD OF WIDENING CROTCH ANGLES OF FRUIT TREESMartin J. Bukovac, 2015 Brentwood Ave., East Lansing, Mich. 48823 NoDrawing. Filed Nov. 14, 1966, Ser. No. 593,730 9 Claims. (Cl. 712.6)

ABSTRACT OF THE DISCLOSURE I The present invention relates to a methodof modifying the growth characteristics of plants, and more particularlyit relates to a method of widening crotch angles in fruit treesutilizing halogenated benzoic acid compounds. Wider crotch angles aredesirable for purposes of strengthening tree framework so as to supportlarge crops of mature fruit.

This application is a continuation-in-part of my copending patentapplication entitled: Method of Widening Crotch Angles of Fruit Trees,Ser. No. 346,996, filed Feb. 24, 1964. 7

It is generally recognized that primary branches forming narrow angleswith the main trunk produce structurally weak crotches. Such narrowcrotch angles frequently break under moderate or heavy fruit cropping,and in so doing seriously reduce the productivity of the host tree.Frequently, entire trees are lost so far as productivity is concerned asa result of weakening and secondary infection directly attributed tobreaking of branches at the crotch.

It. is also recognized that trees having narrow crotch angles are proneto winter injury much more so than trees having wider crotch angles. Asa result of such injuries and structural weakness fruit trees arefrequently lost after the grower has made substantial investments inseeking to establish same, so that the most productive years of thetrees bearing cycle are never fully realized.

Experienced horticulturists have long stressed the importance ofselecting wide angle scaffolds in training young fruit trees. It hasbeen found that the critical limit for branch angles is about 45degrees, and that primary branches forming angles less than 45 degreesare generally weak because of bark inclusion.

Thickening of the branch and trunk during early stages of tree growth isso rapid that the barkin the crotch is compressed before the angle canbe filled out with tissue from the crotch cambium. The adjacent bark onthe branch and trunk are thus pushed together and crushed by thetremendous pressure exerted during growth conditions. Eventuallyportions of the bark in the crotch are destroyed, portions may be pushedoutward and still further portions become embedded into the crotch wherenew tissue growth ultimately surrounds it.

The embedded bark prevents the contiguous tissue of the branch and trunkfrom uniting and growing together.

Decay frequently sets into the surrounded bark, and eventually extendsto the surrounding tissue of the plant, thus further weakening thecrotch.

The weakness of the crotch is not attributed to the acuteness of theangle, but rather to bark inclusion which is so likely to occur in thenarrow angled crotches. Thus the greater the degree of bark inclusion,the weaker the crotch.- By selecting crotches of varying angles fromestablished fruit trees it has been shown that a force of 56 lbs.applied one foot from the trunk on a primary branch was sufiicient tobreak a 30 degree crotch, whereas applying a force of 108 pounds onefoot from the ice tree on a primary branch was required to break a 75degree crotch.

Numerous means have been employed in an attempt to modify narrow angledcrotches. Physical means such as tying branches down, placing spreadersbetween the main stem and lateral branches, or attaching weightedobjects to the laterals have been used to cause wide angles to beformed. The merits of such practices are questionable. Usually,.thelabor costs are sufiiciently high so as to prevent widespread use ofsuch operations. Of greater importance, however, is the generalineffectiveness of such physical practices in producing strong crotches.Without question the lateral branches assume a more horizontal positionand from cursory observation the crotch angles appear to have beenwidened. However, upon closer inspection it is readily seen that thecrotch angle itself has not been markedly altered, but rather the changein branch direction occurred in internodes which were still capable ofelongating, and these internodes are generally several nodes removedfrom the trunk or main stem. Moreover, it is difficult to apply thesephysical treatments sufficiently early in the development of a short budin order to effect actual angle change in the resulting crotch.

With the foregoing in mind the principal object of the present inventionmay be said to reside in a method of chemically widening the crotchangles of fruit trees so as to strengthen the overall structure of suchtrees thereby permitting support of large fruit crops without danger ofbreakage of the branches.

These and other objects of the present invention become apparent fromconsideration of the following detailed disclosure.

The present invention is based upon the surprising discovery that ifcertain chemical agents, such as hereinafter defined, are applied tofruit trees during their early vegetative state of growth, but prior tothe trees reaching the fruiting stage, the growth of such plants will beso altered that the crotch angles between the branches and limbs thereofwill be sufiiciently widened and thus strengthened so as to enable thetree to support large fruit crops during subsequent bearing years.

The chemical agents which have been found to be suitable for use in theprocess of the present invention are 2,3,S-trichlorobenzoic acid;2,3,6-trichlorobenzoic acid;

.2,3,5,6-tetrachlorobenzoic acid and 2,3,5-triiodobenzoic acid, as wellas the functional derivatives such as their amines, amides, esters andsalts.

Hereinafter in the specification, and in the claims appended heretoreference to one or more of the compounds 2,3,5-trichlorobenzoic acid;2,3,6-trichlorobenzoic acid; 2,3,5,6-tetrachlorobenzoic acid and2,3,5-triiodobenzoic acid will be understood as applying equally to theamide of each of such acids; to salts thereof, such as the sodium,potassium or ammonium salts; to amines thereof such as for example thealkyl amines containing up to 10 carbon atoms in each alkyl chain, andthe alkanol amine salts thereof containing up to 3 carbon atoms in eachalkanol chain; and esters thereof such as for example the lower alkylesters containing from 1 to 10 carbon atoms, as Well as the glycol etheresters typical of which are monoand diethylene glycol esters. It is wellrecognized that the use of functional derivatives of hormone acidsimparts the same general level of activity as do the parent acids, whenthe same level of active hormone agent is utilized.

Application of the compounds of this invention to fruit trees should bemade so as to apply an amount of from 5 to ppm. of such compoundrelative to the solution being sprayed upon the trees. Use ofconcentrations of less than about 5 ppm. produces no appreciable changein crotch angles on most varieties of fruit trees, so that this minimumconcentration should be maintained in order to achieve the beneficialresults of this invention. Conversely, where more than 150 ppm. of thecompound,

relative to the carrier, is employed it has been found that phytotoxicinjury sometimes results to the vegetative portions of the plant.Concentrations of between and 75 ppm. of the compound, relative to thecarrier, have been found to provide consistently excellent results overa wide variety of fruit trees and thus represents the preferred usage.

Inasmuch as different fruit trees, as well as different varieties of agiven species may vary in size, it is substantially impossible todetermine the actual amount of active compound being applied to a treein any particular instance. It has been found that if trees sought to betreated are sprayed until the trees are wet to run-01f that thesurprising results of this invention will be realized.

The time of application of the compounds of the present invention tofruit trees is important since it has been found that the surprisingplant response disclosed herein is realized only when the chemicals areapplied to immature trees during which time the general framework isbeing established before fruiting. Modification of the tree structure bychanging branch crotch angle is accomplished during the first severalyears of the trees growth, before the time when the tree is consideredto be commercially capableof setting fruit to maturity.

It has been found that the preferred time of treatment *by the processof the present invention is accomplished during the lateral shootdeevlopment stages. Moreover, it has been found that treatments by theprocess of the present invention may be accomplished in successive yearsif desired in order to achieve maximum crotch angle modifications.

So far as concerns formulation of the compounds found to be suitable foruse in this invention certain of these compounds, or derivativesthereof, are soluble in aqueous media. For example, certain of thealkali metal and ammonium salts, and the lower alkyl and alkanol aminesalts of the chlorinated or iodinated benzoic acids are sufficientlysoluble in water so as to be capable of spraying in an aqueous solution.Certain other compounds, however, are substantially water insoluble andmust be formulated in suitable organic solvents or agricultural oilsprior to use. This latter type includes the parent acids; the amide ofeach acid; the esters thereof; and certain of the relatively highmolecular weight amines, that is those containing alkyl chain lengthshaving from 6 to 10 carbon atoms. Inasmuch as the techniques forformulation of these halogenated benzoic acids are known in theargricultural industry, sufiice it to say that the water insolubleformulations may be prepared in the usual manner, particularly withreference to the incorporation of emulsifying and/ or wetting agentsinto such compositions where desirable.

The surprising features of this invention are set forth hereinbelow asapplied to various varieties of apple trees. However, such presentationsare not to be construed as in any way limiting the scope of thisinvention since this process has been found to be applicable to fruittrees generally, including such fruit crops as apple, cherry, peach,pear, prune and plum, and thus is not restricted to the treatment of theapplespecies.

Example I TABLE 1 Degree of Crotch Angle Replication TIBA, p.p.m.

Control Degrees Degrees Degrees 49 81 65 45 62 65 39 57 59 22 55 5 28 6459 Average. 37 64 68 Example II Year-old apple trees of the RedDelicious type (Evarts, Redspur and Wellspur strains) were sprayed withsolutions containing 30 and 50 ppm. of 2,3,5-triiodobenzoic acid (TIBA)equivalent. Spraying was conducted during the spring growing season andwas continued until the trees were Wet to run-off with the aqueoussolutions. Determinations of crotch angle formations on limbs for eachtreatment of these treated trees were made and are re corded by way ofcomparison in Table II wherein the number of branches for each degreeclassification is shown in comparison with controls.

Two-year old apple trees of the Red Delicious type (Evarts strain) weresprayed until wet to run-off using aqueous solutions containing 50 ppm.of the respective chlorinated benzoic acid compounds as listed below inTable III. Spraying was effected during the spring season when the treeswere in an active state of growth, and at the time of spraying lateralshoots on the apple trees were 4 to 5 inches in length. Observations ofthe eflects of these compounds on crotch angles were obtained usingactual angle measurements, and are reported below in Table III incomparison with control or untreated trees.

TABLE III Degree of Crotch Angle Replication 2,4,5-tri- 2,3,6-tri-2,3,5,6-'

Control chlorochlorotetra- (deg.) benzoic benzoic chloroaeid (deg) acid(deg) benzoic acid (deg) Average..' 56. l 73. 2 85. 9 75. 5

It is evident from the data reported in Tables I, II and III above thatwidening of the crotch angles of fruit trees is accomplished inaccordance with the process of the present invention, thereby providingfor selection of wide angled laterals which, in future bearing years,will be more able to support the weight of mature fruit.

What is claimed as the invention is: 1. A method of widening the crotchangles of fruit trees which comprises spraying on immature fruit trees achlori-' nated benzoic acid compound selected from the group consistingof 2,4,5-trichlorobenzoic acid; 2,3,6-trichlorobenzoic acid; and2,3,5,6-tetrachlorobenzoic acid, said acid compound being applied duringthe vegetative development stage and before the trees reach the fruitingstage in a concentration sufiicient to widen crotch angles withoutcausing phytotoxic eflects.

27 The method of claim 1 wherein the benzoic acid compound is admixedwith a carrier in a concentration of between 5 and 150 parts of the acidcompound to one million parts of the carrier and the mixture is sprayedon the trees.

3. The method of claim 1 wherein the benzoic acid compound is admixedwith a carrier in a concentration of between 25 and 7 5 parts of theacid to one million parts of the carrier and the admixture is sprayed onthe trees.

4. The method of claim 1 wherein the fruit tree is apple. 5. The methodof claim 1 wherein the fruit tree is cherry.

. The method of claim 1 wherein the fruit tree is pear. The method ofclaim 1 wherein the fruit tree is peach. The method of claim 1 whereinthe fruit tree is prune. The method of claim 1 wherein the fruit tree isplum.

References Cited UNITED STATES PATENTS 2,978,838 4/1961 Beatty 7l2.6 X

LEWIS GOTTS, Primary Examiner.

JAMES O. THOMAS, JR., Examiner.

1. A METHOD OF WIDENING THE CROTCH ANGLES OF FRUIT TREES WHICH COMPRISESSPRAYING ON IMMATURE FRUIT TREES A CHLORINATED BENZOIC ACID COMPOUNDSELECTED FROM THE GROUP CONSISTING OF 2,4,5-TRICHLOROBENZOIC ACID;2,3,6-TRICHLOROBENZOIC ACID; AND 2,3,5,6-TETRACHLOROBENZOIC ACID, SAIDACID COMPOUND BEING APPLIED DURING THE VEGETATIVE DEVELOPMENT STAGE ANDBEFORE THE TREES REACH THE FRUITING STAGE IN A CONCENTRATION SUFFICIENTTO WIDEN CROTCH ANGLES WITHOUT CAUSING PHYTOTOXIC EFFECTS.